/**
 * @param {character[]} s
 * @return {void} Do not return anything, modify s in-place instead.
 */
var reverseString = function(s) {
    let left = 0
    let right = s.length-1
    while (left < right) {
        let temp = s[right]
        s[right] = s[left]
        s[left] = temp
        right--
        left++
    }
    return s

};
let s = ["h","e","l","l","o"]
console.log(reverseString(s))